1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 24 */ 25 /* 26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 27 * Use is subject to license terms. 28 */ 29 30 #pragma weak __ilogbf = ilogbf 31 32 #include "libm.h" 33 #include "xpg6.h" /* __xpg6 */ 34 35 #if defined(__x86) 36 static const float two25 = 33554432.0F; 37 #else 38 /* 39 * v: a non-zero subnormal |x| 40 */ 41 static int 42 ilogbf_subnormal(unsigned v) { 43 int r = -126 - 23; 44 45 if (v & 0xffff0000) 46 r += 16, v >>= 16; 47 if (v & 0xff00) 48 r += 8, v >>= 8; 49 if (v & 0xf0) 50 r += 4, v >>= 4; 51 v <<= 1; 52 return (r + ((0xffffaa50 >> v) & 0x3)); 53 } 54 #endif /* defined(__x86) */ 55 56 static int 57 raise_invalid(int v) { /* SUSv3 requires ilogbf(0,+/-Inf,NaN) raise invalid */ 58 #ifndef lint 59 if ((__xpg6 & _C99SUSv3_ilogb_0InfNaN_raises_invalid) != 0) { 60 static const double zero = 0.0; 61 volatile double dummy __unused; 62 63 dummy = zero / zero; 64 } 65 #endif 66 return (v); 67 } 68 69 int 70 ilogbf(float x) { 71 int k = *((int *) &x) & ~0x80000000; 72 73 if (k < 0x00800000) { 74 if (k == 0) 75 return (raise_invalid(0x80000001)); 76 else { 77 #if defined(__x86) 78 x *= two25; 79 return (((*((int *) &x) & 0x7f800000) >> 23) - 152); 80 #else 81 return (ilogbf_subnormal(k)); 82 #endif 83 } 84 } else if (k < 0x7f800000) 85 return ((k >> 23) - 127); 86 else 87 return (raise_invalid(0x7fffffff)); 88 } 89